Functional fluids are lubricants used in enclosed systems to transmit power. Examples of systems where functional fluids are used include shock absorbers, hydraulic systems, power steering systems, and transmissions. Shock absorber fluids are low viscosity oils that must operate at a wide temperature range, especially high temperature. Current oils often fail due to high temperature and may even get so hot that they melt the paint on the shock absorbers. Current shock absorber fluids are made using a petroleum derived base oil that is a pale oil spindle oil, and the shock absorber fluids have a viscosity index of less than 130, a Brookfield viscosity at −30° C. of 1000 mPa.s, an air release after 1 minute by DIN 51831 of greater than 1.0 vol %, and an aniline point less than 95° C.
Improvements in functional fluids, and specifically shock absorber fluids are needed, without having to use highly expensive synthetic base oils.